4,947 research outputs found
A Coronal Hole's Effects on CME Shock Morphology in the Inner Heliosphere
We use STEREO imagery to study the morphology of a shock driven by a fast
coronal mass ejection (CME) launched from the Sun on 2011 March 7. The source
region of the CME is located just to the east of a coronal hole. The CME ejecta
is deflected away from the hole, in contrast with the shock, which readily
expands into the fast outflow from the coronal hole. The result is a CME with
ejecta not well centered within the shock surrounding it. The shock shape
inferred from the imaging is compared with in situ data at 1 AU, where the
shock is observed near Earth by the Wind spacecraft, and at STEREO-A. Shock
normals computed from the in situ data are consistent with the shock morphology
inferred from imaging.Comment: to appear in The Astrophysical Journa
Structure of Flame Balls at Low Lewis-Number (SOFBALL): Preliminary Results From the STS-83 and STS-94 Space Flight Experiments
Results from the Structure Of Flame Balls At Low Lewis-number (SOFBALL) space flight experiment conducted on the MSL-1 Space Shuttle missions are reported. Several new insights were obtained, including: much lower buoyancy-induced drift speed than anticipated pre-flight; repulsion of adjacent flame balls due to their mutual interaction; remarkable sensitivity of flame balls to small accelerations resulting from Orbiter attitude control maneuvers; and very similar net heat release for all flame balls in all mixtures tested. Comparison of experimental results to computational predictions reveals limitations in current models of H2-02 chemistry for very lean mixtures. It is discussed how the results of these space experiments may provide an improved understanding of the interactions of the two most important phenomena in combusting materials, namely chemical reaction and transport processes, in the unequivocally simplest possible configuration
A Substellar Companion in a 1.3 yr Nearly-circular Orbit of HD 16760
We report the detection of a substellar companion orbiting the G5 dwarf HD
16760 from the N2K sample. Precise Doppler measurements of the star from Subaru
and Keck revealed a Keplerian velocity variation with a period of 466.47+-0.35
d, a semiamplitude of 407.71+-0.84 m/s, and an eccentricity of 0.084+-0.003.
Adopting a stellar mass of 0.78+-0.05 M_Sun, we obtain a minimum mass for the
companion of 13.13+-0.56 M_JUP, which is close to the planet/brown-dwarf
transition, and the semimajor axis of 1.084+-0.023 AU. The nearly circular
orbit despite the large mass and intermediate orbital period makes this
companion unique among known substellar companions.Comment: 14 pages, 2 figures, accepted for publication in Ap
Glycoproteomic studies of IgE from a novel hyper IgE syndrome linked to PGM3 mutation
International audienceGlycans serve as important regulators of antibody activities and half-lives. IgE is the most heavily glycosylated antibody, but in comparison to other antibodies little is known about its glycan structure function relationships. We therefore describe the site specific IgE glycosylation from a patient with a novel hyper IgE syndrome linked to mutations in PGM3, which is an enzyme involved in synthesizing UDP-GlcNAc, a sugar donor widely required for glycosylation. A two-step method was developed to prepare two IgE samples from less than 1 mL of serum collected from a patient with PGM3 mutation and a patient with atopic dermatitis as a control subject. Then, a glycoproteomic strategy was used to study the site-specific glycosylation. No glycosylation was found at Asn264, whilst high mannose glycans were only detected at Asn275, tri-antennary glycans were exclusively observed at Asn99 and Asn252, and non-fucosylated complex glycans were detected at Asn99. The results showed similar glycosylation profiles between the two IgE samples. These observations, together with previous knowledge of IgE glycosylation, imply that IgE glycosylation is similarly regulated among healthy control, allergy and PGM3 related hyper IgE syndrome
Transcript-indexed ATAC-seq for precision immune profiling.
T cells create vast amounts of diversity in the genes that encode their T cell receptors (TCRs), which enables individual clones to recognize specific peptide-major histocompatibility complex (MHC) ligands. Here we combined sequencing of the TCR-encoding genes with assay for transposase-accessible chromatin with sequencing (ATAC-seq) analysis at the single-cell level to provide information on the TCR specificity and epigenomic state of individual T cells. By using this approach, termed transcript-indexed ATAC-seq (T-ATAC-seq), we identified epigenomic signatures in immortalized leukemic T cells, primary human T cells from healthy volunteers and primary leukemic T cells from patient samples. In peripheral blood CD4+ T cells from healthy individuals, we identified cis and trans regulators of naive and memory T cell states and found substantial heterogeneity in surface-marker-defined T cell populations. In patients with a leukemic form of cutaneous T cell lymphoma, T-ATAC-seq enabled identification of leukemic and nonleukemic regulatory pathways in T cells from the same individual by allowing separation of the signals that arose from the malignant clone from the background T cell noise. Thus, T-ATAC-seq is a new tool that enables analysis of epigenomic landscapes in clonal T cells and should be valuable for studies of T cell malignancy, immunity and immunotherapy
A Survey of Extragalactic Faraday Rotation at High Galactic Latitude: The Vertical Magnetic Field of the Milky Way towards the Galactic Poles
We present a study of the vertical magnetic field of the Milky Way towards
the Galactic poles, determined from observations of Faraday rotation toward
more than 1000 polarized extragalactic radio sources at Galactic latitudes |b|
> 77 degs, using the Westerbork Radio Synthesis Telescope and the Australia
Telescope Compact Array. We find median rotation measures (RMs) of 0.0 +/- 0.5
rad/m^2 and +6.3 +/- 0.7 rad/m^2 toward the north and south Galactic poles,
respectively, demonstrating that there is no coherent vertical magnetic field
in the Milky Way at the Sun's position. If this is a global property of the
Milky Way's magnetism, then the lack of symmetry across the disk rules out pure
dipole or quadrupole geometries for the Galactic magnetic field. The angular
fluctuations in RM seen in our data show no preferred scale within the range ~
0.1 to 25 degs. The observed standard deviation in RM of ~ 9 rad/m^2 then
implies an upper limit of ~1microGauss on the strength of the random magnetic
field in the warm ionized medium at high Galactic latitudes.Comment: 38 pages, 7 figures, 3 tables Accepted for publication in ApJ,
Electronic versions of Tables 1 and 2 are available via email from the first
autho
Constraints on the Minimal Supergravity Model with Large
In the minimal supergravity model (mSUGRA), as the parameter
increases, the charged Higgs boson and light bottom squark masses decrease,
which can potentially increase contributions from , \tg\tb_j and
\tz_i\tb_j loops in the decay . We update a previous QCD
improved decay calculation to include in addition the effects of
gluino and neutralino loops. We find that in the mSUGRA model, loops involving
charginos also increase, and dominate over , , \tg\tq and
\tz_i\tq contributions for \tan\beta\agt 5-10. We find for large values of
that most of the parameter space of the mSUGRA model for
is ruled out due to too large a value of branching ratio . For and large , most of parameter space is
allowed, although the regions with the least fine-tuning (low and
) are ruled out due to too low a value of . We
compare the constraints from to constraints from the neutralino
relic density, and to expectations for sparticle discovery at LEP2 and the
Fermilab Tevatron colliders. Finally, we show that non-universal GUT
scale soft breaking squark mass terms can enhance gluino loop contributions to
decay rate even if these are diagonal.Comment: 14 page REVTEX file plus 6 PS figure
Discovery and Rossiter-McLaughlin Effect of Exoplanet Kepler-8b
We report the discovery and the Rossiter-McLaughlin effect of Kepler-8b, a
transiting planet identified by the NASA Kepler Mission. Kepler photometry and
Keck-HIRES radial velocities yield the radius and mass of the planet around
this F8IV subgiant host star. The planet has a radius RP = 1.419 RJ and a mass,
MP = 0.60 MJ, yielding a density of 0.26 g cm^-3, among the lowest density
planets known. The orbital period is P = 3.523 days and orbital semima jor axis
is 0.0483+0.0006/-0.0012 AU. The star has a large rotational v sin i of 10.5
+/- 0.7 km s^-1 and is relatively faint (V = 13.89 mag), both properties
deleterious to precise Doppler measurements. The velocities are indeed noisy,
with scatter of 30 m s^-1, but exhibit a period and phase consistent with the
planet implied by the photometry. We securely detect the Rossiter-McLaughlin
effect, confirming the planet's existence and establishing its orbit as
prograde. We measure an inclination between the projected planetary orbital
axis and the projected stellar rotation axis of lambda = -26.9 +/- 4.6 deg,
indicating a moderate inclination of the planetary orbit. Rossiter-McLaughlin
measurements of a large sample of transiting planets from Kepler will provide a
statistically robust measure of the true distribution of spin-orbit
orientations for hot jupiters in general.Comment: 26 pages, 8 figures, 2 tables; In preparation for submission to the
Astrophysical Journa
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